WASHINGTON — President Barack Obama announced Thursday that his administration will investigate to see if fraud or manipulation in oil markets is behind the spike in gasoline prices.

"We are going to make sure that no one is taking advantage of the American people for their own short-term gain," Obama said at a town hall meeting in Reno, Nev.

He vowed that a broad government task force under Attorney General Eric Holder would "root out any cases of fraud or manipulation" in gasoline prices — "and that includes the role of traders and speculators."

Financial speculation is widely considered to be a possibly prime factor driving up global oil prices. Despite turmoil in the Middle East, there's been no significant interruption of oil production, and supplies remain abundant. Meanwhile, financial institutions have been purchasing contracts for future oil delivery as an investment strategy, driving up prices.

Other factors believed contributing to the rising prices are fear of future supply interruption rising from Middle East turmoil and projections of rising oil demand as the global economy recovers.

Obama's under political pressure to address gasoline prices that are nearing an average of $4 a gallon. The average price of regular this week hit $3.84 per gallon, according to AAA, up 30 cents in a month and almost a dollar from a year ago.

A McClatchy-Marist poll this week showed that only 11 percent of drivers blame Obama and the Democrats. Still, the sticker shock at the pump likely contributed to a drop in Obama's overall job approval and a big increase in the ranks of Americans who feel the country's headed in the wrong direction — a significant political barometer now at the worst level since November 2007.

In Washington, Holder announced that a Financial Fraud Enforcement Task Force Working Group, comprised of regulators from many federal financial agencies, would focus on fraud in energy markets. An Oil and Gas Price Fraud Working Group would probe oil and gas markets for potential violations of civil or criminal laws. It also will examine commodities markets and the role of speculators and index traders in oil futures markets, he said.

"Rapidly rising gasoline prices are pinching the pockets of consumers across the country," Holder said in a statement. "We will be vigilant in monitoring the oil and gas markets for any wrongdoing."

Speculation has been on regulators' minds as oil prices have climbed from the $80 range late last year to more than $112 a barrel Thursday.

There's no shortage of oil supplies, with excess production capacity globally and flat demand as the global economic recovery remains sluggish. McClatchy has reported on the impact of financial speculation on oil and gasoline prices since 2008.

One regulator whose agency will participate said this task force isn't for public relations purposes alone. In the past when oil prices soared, prosecutors tried to make examples of gas station owners or middlemen profiting from climbing prices. This task force is looking at financial markets, and seeking much bigger targets.

"We are definitely looking at trading in the markets that isn't nickel-and-dime stuff. They're big enough that we would want the Justice Department involved. We would want people potentially to go to jail," said the regulator, who requested anonymity to speak freely about ongoing investigations.

Commodities markets rely on speculation, which isn't necessarily a bad thing; it's excessive speculation that regulators are trying to curb.

Bart Chilton, a Commodities Futures Trading Commissioner, whose panel regulates futures markets, has argued that speculation is excessive. But he said that determining how much of the oil price spike stems from speculation, rather than a "fear premium" rising from Middle East instability, isn't a simple calculation.

"It really is more nuanced than that," he said. "They're having an impact, and I think a fairly large impact. It's adding several dollars to the cost of a fill-up."

"Up until recently, 75 percent of our criminal referrals to Justice were rejected. We end up with decent outcomes, but nobody goes to jail because it's not criminal prosecution if we do it," Chilton said, referring to the CFTC.

He tried unsuccessfully to convince Congress last year to give the agency the power to bring criminal charges in such instances, instead of civil cases that yield fines but do little do deter big Wall Street firms.

Large-scale investment from big institutional investors, such as pension funds, is also thought to be pushing up oil prices. They're buying up contracts for future delivery of oil on the assumption that prices will just keep going up. Futures markets are designed to hedge against price shifts, but these new players treat their oil contracts like stocks.